Kaposi's sarcoma-associated herpesvirus (KSHV) belongs to the lymphotropic gamma herpesviridae. In immunocompromised patients, such as organ transplant recipients and AIDS patients, KSHV infection is invariantly associated with Kaposi's sarcoma, a skin angiogenic neoplasm. Additionally, KSHV is the etiological agent for two rare lymphoproliferative diseases, primary effusion lymphoma and multicentric Castleman's disease. The oncogenic potential and relatively ubiquitous infection imposes an eminent health threat worldwide. Understanding fundamental virology and host immune response are two sides of the same coins of KSHV infection and will pave new avenues to treat KSHV-associated malignancies. Innate immunity is the first line of defense against invading pathogens. Recent advances have outlined the framework of signal transduction in mounting host innate immune response. However, the specific functions of key innate immune components, e.g., the IKK-related kinase IKKe, remain contentious. We have recently discovered that the IKKs kinase restricts gamma herpesvirus lytic replication and enables latent/persistent infection. This study proposes to investigate the molecular mechanisms by which the IKKE kinase negates KSHV lytic replication, thereby enabling persistent infection! We will characterize virus-host interactions involving the IKKe kinase (Aim 1), define the regulatory action of IKKs on KSHV lytic replication (Aim 2), and finally assess the roles of IKKe and viral interactions thereof in KSHV persistent infection using a humanized mouse model. This proposal entails a powerful reverse genetic system to perturb virus-host interactions and investigate the roles of these interactions in KSHV lytic replication and persistent infection. The application of lytic replicating system and an animal model will identify key interactions and define mutual regulations of in vivo KSHV infection, instructing us on new ways to contain KSHV infection.